Jewellery Hinge Assembly With Adjustable Clearance and Low-Wear Inserts
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Solution Overview
Problem
Small hinges used in the horological and jewellery industries, with guide body diameters of less than 2 millimetres, fail to withstand fatigue, bending, torsion, and wear, particularly when made from materials like gold and platinum alloys, and often require oversized designs to compensate for stress zones, leading to compatibility issues with luxury parts.
Innovation Solution
A hinge assembly with an outer and inner hinge system that includes angular indexing means and a screw-tube-nut arrangement, using materials like polyamide 11 or polytetrafluoroethylene to distribute stress and reduce wear, featuring a guide tube and tube-nut with adjustable axial clearance and tightness, and angular indexing to enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the hinge is made with very small dimensions (guide body diameter less than 2mm), then it is compatible with luxury parts, but it fails to withstand fatigue, bending, and torsion
Solution Approach 1:
The hinge is divided into separate components: an outer hinge piece with guide body and guide tube, and an inner hinge piece with knuckle and tube-nut. This segmentation allows each component to be optimized for its specific function while maintaining overall small dimensions, enabling the hinge to fit luxury parts while distributing mechanical stresses across multiple elements rather than concentrating them in a single small structure.
Solution Approach 2:
The invention uses composite construction by combining different materials: the guide tube and tube-nut are made from polyamide 11 or polytetrafluoroethylene (low-friction materials), while the hinge pieces can be made from various materials including precious metal alloys. This composite approach allows the small hinge to withstand fatigue, bending, and torsion by selecting materials with appropriate mechanical properties for each component.
2Adaptability or versatility
If traditional hinge materials like gold and platinum alloys are used, then the hinge is suitable for luxury parts, but friction in the bores quickly leads to wear
Solution Approach 1:
The guide tube and tube-nut act as intermediary elements between the moving parts of the hinge. These components are specifically made from low-friction materials (polyamide 11 or polytetrafluoroethylene) that reduce wear and friction during operation. This intermediary approach allows the hinge to maintain precious metal aesthetics while the polymer components handle the friction and wear, solving the reliability issue without compromising luxury compatibility.
Solution Approach 2:
The invention changes the material parameter of the guide tube and tube-nut from traditional precious metals to polymers with low coefficients of friction (polyamide 11 or polytetrafluoroethylene). This parameter change specifically targets the friction and wear properties while allowing other parts of the hinge to maintain their luxury appearance and compatibility, thus improving reliability without sacrificing adaptability to luxury applications.
3Reliability
If the hinge screw is tightened to increase friction, then operational reliability improves, but torsional stresses are generated
Solution Approach 1:
The invention replaces the traditional screw-nut mechanical fastening system with a press-fit system using elastic deformation. The guide tube is inserted into the outer hinge piece's guide body bore, and the tube-nut is pressed into the inner hinge piece's knuckle bore. This substitution eliminates the need for tightening screws that generate torsional stresses, while still providing secure assembly and allowing for friction-based operational reliability through the elastic interference fit.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The hinge assembly provides enhanced resistance to bending and torsion, reduces wear, and ensures long-term operational reliability, suitable for high-end timepieces and jewellery, by optimizing stress distribution and using low-friction materials.
Implementation Method 1
Another aspect of the invention relates to the manufacture of the tube-nut and/or of said guide tube from polyamide 11 or polyamide 6-6 or polytetrafluoroethylene or high-density polyethylene
Data Source
AI summary
A horological or jewellery hinge assembly including an outer hinge with a first and a second knuckle and an inner hinge with a single knuckle, which pivot about a screw passing through a guide tube insertable and indexed rotatably in the first knuckle and a tube-nut insertable in the second knuckle, and axially immobilised by a head in the guide tube and including a thread cooperating with an internal thread of the tube-nut, for adjusting the axial clearance or tightness between the outer hinge and the inner hinge, the tube-nut being indexable rotatably in the second knuckle, the tube-nut or the guide tube being advantageously made of polyamide or polytetrafluoroethylene or high-density polyethylene.